The induction of crown-gall tumors by bacteria in the genus Agrobacterium will be utilized as a model system for studying the genetics and biochemistry of carcinogenesis. Various strains of Agrobacterium will be analyzed for ability to undergo genetic recombination by means of transformation, transduction and conjugation. Conditions and procedures providing for optimal recombination will be defined. These techniques will then be employed to characterize infectious and non-infectious mutants of the bacterium to determine the nature of the cistrons responsible for induction and maintenance of autonomous growth.